1. Field of the Invention
This invention relates to a blood lancet extraction and disposal assembly for use with an automatic lancet device of the type commonly used for taking skin capillary blood samples, and more specifically, it relates to an assembly wherein means are provided to resist undesired lancet puncture wounds during and after removal of the disposable lancet from the automatic lancet device.
2. Description of the Prior Art
Blood lancets are used for drawing a small amount of blood, e.g. for diagnostic purposes, by a short prick, preferably into the ball of the finger. As a rule, one uses sterile disposable lancets to avoid the danger of infection. Blood lancets which are stamped out of a thin metal sheet are common.
Another kind of blood lancet consists of a hub (or handle) injection molded of plastic in one piece with an integrally molded steel tip. The tip of these blood lancets is relatively blunt because on the one hand, a fine tip is difficult to produce by injection molding and, on the other hand, a fine tip easily breaks off during transport and storage. To make and protect a fine tip, the tip is surrounded by a plastic protective cap which is extruded in one piece with retaining attachment points and is twisted off before use of the lancet.
Holman et al, in U.S. Pat. No. 4,230,118, describe an automatic lancet device for use in pricking a patient's skin to yield a blood sample. The device comprises an arm, one end of which arm is pivotally mounted in a housing and its other, or outer, end protruding from the housing through an arcuate slot in the housing, the outer end of the arm being formed into a carrier which will hold a replaceable mountable lancet with its point projecting tangentially to the pivotal arc of the arm. The arm is spring biased in the angular direction corresponding to the direction in which the lancet points and can be held retracted against the spring means by a latch in the housing. When the latch is released, the arm springs forward causing the lancet attached thereto to strike a detachable finger rest. The detachable finger rest which is mounted in the housing, includes a ring for resting on the patient's skin so that the sharp lancet tip projects through the ring for pricking.
Leopoldi et al, in U.S. Pat. No. 4,452,243, describe another automatic blood lancet device which includes a fingertip element to be held by a user and a hinged striker element pivotally mounted on the device and spring-actuated to drive a lancet secured on the striker into the fleshy fingertip. A thumb piece on the striker is provided to draw the striker back into a cocked position. This device is intended for use with a lancet that has a twist-off or tear-away protective cap for maintaining the sanitary condition of the lancet until it is to be used. The striker element is flexible and the finger grip element is provided with an upstanding projection on the top surface, which the striker contacts and about which the striker flexes when it is spring-actuated downwardly about its pivot, whereby the puncturing element is thrust downwardly below the bottom surface of the finger grip element to puncture the flesh and then be retracted upwardly when it rebounds to dispose the puncture element substantially above such bottom surface in a withdrawn position.
Both the Holman and Leopoldi inventions described above provide a hinged striker element of flexible construction for driving a sharp puncturing device such as a lancet into the fleshy fingertip pad and which is integrally associated with a mounting element that includes a generally flat surface member on which the striker element is pivotally secured for hinged movement. The lancet, when used in either device, must be removed manually and without the protection of a safety cap.
In 1983, the Center for Disease Control published a document entitled "Guideline for Isolation Precautions in Hospitals" that contained a section entitled "Blood and Body Fluid Precautions." The recommendations in this section called for precautions in handling blood and body fluids when a patient was known or suspected to be infected with blood borne pathogens. Partly in response to the serious risk to hospital workers exposed to patients infected with the HIV virus, CDC published a more detailed guideline entitled, "Recommendations for Prevention of HIV Transmission in Health Care Settings" in August, 1987. In contrast to the 1983 document, the 1987 document recommended that blood and body fluid precautions be consistently used for all patients regardless of their blood-borne infection status. This extension of blood and body fluid precautions to all patients is referred to as "universal blood and body fluid precautions" or simply "universal precautions." Under universal precautions, blood and certain body fluids of all patients are considered potentially infectious for human immune deficiency virus (HIV), hepatitis B virus (HBV), and other blood-borne pathogens.
Universal precautions are intended to prevent contact, and exposure of health care workers to blood-borne pathogens. In addition, immunization with HBV vaccine is recommended as an important adjunct to universal precautions for health care workers who have exposures to blood.
Much attention has gone into protecting workers from needle stick injuries. Such accidental needle stick injuries have even resulted in transmission of the HIV virus to the workers. Accidental needle sticks with needles which have had patient contact commonly result in transmission of viral hepatitis. Other diseases which may be transmitted in like fashion are herpes, streptococcus, staphylococcus, tuberculosis, malaria and syphilis.
Many innovative devices have been developed to address the problem of preventing accidental needle-stick injuries. U.S. Pat. No. 4,356,822 discloses a syringe assembly wherein an outer tubular member is adapted to control the depth of needle penetration into the patient. Smith, Jr., in U.S. Pat. No. 4,643,722 describes a slotted needle sheath hinged to the hub of the needle. Luther, in U.S. Pat. No. 4,747,836 describes another needle guard which is a slotted tube which slips over the needle.
In spite of the foregoing work with needles, nothing has been done to protect hospital workers or other health care providers from accidental sticks from a lancet. In general, in regard to lancets, existing systems provide a cap member having a closed end wall positioned over the lancet which is attached to the hub or base portion of the lancet. The cap is removed by breaking it away from the hub portion at breakaway points which are molded into the hub. Normally, the lancet may be disposed of by merely discarding without capping inasmuch as the cap is provided to protect the sharp point prior to use and is not generally suitable for recapping the lancet. Rigid boxes ("sharps" containers) having suitable openings for receipt of used lancets are commonly employed.
There remains a significant need for an extraction and closure member for lancets which will effectively cover the lancet tip, maintain sterility, if necessary, and minimize the risk of accidental puncture wounds both during and after removal of the lancet from an automatic lancet device.